1. Field of the Invention
The invention relates to a method for adhering one surface to another surface and, more particularly, to a method for mounting a semiconductor wafer on a support by means of a mixture comprising a chloronaphthalene and a terphenyl.
2. Description of the Prior Art
Semiconductor devices are formed in a wafer of semiconductor material and the wafer is mounted on a carrier or support by cementing it thereto with polypropylene or a wax, such as that solid by the Biwax Corporation under the trade designation "B-7050." The wafer is then thinned by lapping and etched into individual devices. This produces an array of hundreds of devices which have been formed as close together as possible in order to obtain the maximum number of devices from the semiconductor wafer.
The close-packed array contains both acceptable and unacceptable devices, and, for economy of further manufacturing operations, the acceptable devices are transferred from the support on which they were formed to another support in an expanded array. This may be done as disclosed in copending application, Ser. No. 307,898, filed Nov. 20, 1972 or No. 517,698, filed Oct. 24, 1974, which are assigned to the same assignee as this application.
As disclosed in application Ser. No. 517,698, the waxes used in the prior art polymerize and/or oxidize on prolonged heating at the elevated temperatures required for device removal. Such chemically changed wax is difficult to remove and it is essential that any such wax be removed to avoid contaminating the chips and interfering with subsequent bonding to circuit boards. Thus, prolonged heating at the elevated temperatures should be avoided in order to prevent polymerization and/or oxidation of the polypropylene or waxes.
Another way of avoiding the effects of prolonged heating is to use stable hydrocarbon compounds which will evaporate completely and at relatively low temperatures. M. L. White discloses, in U.S. Pat. No. 3,752,717, an adhesive consisting essentially of at least one of the following: fluorene, phenanthrene, anthracene, octadecane, eicosane, docosane, and tetracosane. These vaporize completely without leaving residues.
Further, improvement may be made over this prior art through the use of combinations of naphthalene and benzene compounds which adhere better and also vaporize leaving no residue.